In maritime electronic warfare environments, array receiving systems estimate the azimuth and elevation of emitter signals. However, sea-surface reflections cause direct and multipath components to be observed simultaneously, leading to angular estimates that deviate from the true direction of arrival. Because these components are strongly correlated, and the sign of the elevation angle is not reflected in the inter-element phase differences of a uniform circular array, the two paths cannot be sufficiently separated, degrading the estimation accuracy. To address this issue, a direction-of-arrival estimation method based on a double-layer uniform circular array is proposed. The proposed structure employs two circular arrays with identical vertical separation radii. The nonlinear phase structure is transformed into a linear beamspace representation, and forward–backward spatial smoothing is applied to enhance the separation performance. The simulation results demonstrate improved estimation accuracy compared to a conventional single-layer uniform circular array.
Lee et al. (Fri,) studied this question.